Thai Pilots Flying to Be Rainmakers

Planes stationed at airfields around Thailand take to the skies almost daily, flying sorties in a campaign of national importance -- a war on the country’s worst drought in seven years.

They take off loaded not with bombs but with rainmaking chemicals -- prepared to specifications personally developed by King Bhumibol Adulyadej, who is commanding the operation.

On the flight line in this seaside town, aviators wear uniforms with shoulder patches proudly describing their duty: “Cloud Attackers.”

After loading the appropriate chemicals, a small Indonesian-made plane makes a morning takeoff and gains an altitude of 5,000 feet chasing some clouds, which can be hard to catch.

“If there is a strong wind, it can move the cloud away,” pilot Jiti Tewan said.

Once the target is sighted, the crew sprays sodium chloride into the atmosphere through a tube at the rear of the plane.

“These are little clouds. We will have to create more clouds by forming a skeletal structure for water vapor to cling on to,” said a technician, Sumol Butsaendee.

There are two more stages to go. A few hours later, pilots use a smaller aircraft to make a bumpy run through the lower layers of the clouds and spray dry ice to “fatten” the clouds with greater humidity. On a final run, other chemicals are sprayed to lower the clouds’ temperature, which is supposed to trigger rain.

This year’s drought, which is also affecting neighboring countries, has damaged 5.2 million acres of farmland, and has caused $191 million in economic losses. More than 9 million of the 63 million people in almost all of Thailand’s 76 provinces are short of water. Some rains in early April didn’t put a dent the problem.

Reservoirs in the poverty-stricken northeast, where most people farm for a living, are down to less than 8% of capacity.

The revered 77-year-old king called the government’s attention to the problem in early March. That led the government to set up a rainmaking center at Hua Hin, the town 143 miles south of Bangkok where the king’s summer palace is located.

The constitutional monarch, who for decades has studied and promoted water management as essential for development, was put in command, and the center manages cloud-seeding flights from nine airfields around the country.

Cloud-seeding, which dates to the 1940s, is a controversial process among weather experts, with many scientists arguing that its efficacy is limited and unproven. But it is widely used all over the world.

Generally, it relies on such chemicals as silver iodide to form ice crystals that melt as they fall through a storm cloud.

In Thailand, cloud seeding has a powerful patron in the king. Based on his decades of study and observation, he has come up with his own cloud-seeding process.

His formula, invented in 1971, is being considered for patents in the U.S. and Europe, says Wattana Sukarnjanaset, director of the Hua Hin Rainmaking Center. He says countries including Malaysia, Indonesia and the Philippines have sought technical assistance from Thailand.

A recent Interior Ministry report said the Thai rainmaking effort had helped ease the dearth of rain in six provinces that account for 26% of the land affected by the drought. But more than 4,000 villages nationwide do not have enough water for consumption, let alone farming.